1. Field of the Invention
The invention relates generally wireless to communications technology. More particularly, an embodiment of the invention determines signal characteristics for transmissions using Orthogonal Frequency Division Multiplexing (OFDM).
2. Background Art
Modern wireless communication systems frequently rely on the advantages of OFDM and Orthogonal Frequency Division Multiple Access (OFDMA) techniques, referred to collectively herein as OFDM(A). In particular, wireless technology commonly implements Institute of Electrical and Electronics Engineers (IEEE) standards such as the IEEE 802.16 standards for Wireless Metropolitan Area Networks (WMANs), including the IEEE 802.16e IEEE Standard for Local and Metropolitan Area Networks—Part 16: Air Interface for Fixed Broadband Wireless Access Systems-Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands, 2004.
One of the advantages of OFDM(A) communications is the ability to use link adaptation (LA), wherein modulation, coding and other signal or protocol parameters can be adjusted according to the signal transmission environment. Fast link adaptation methods significantly improve throughput and data packet error rate (PER) performance of OFDM(A) system in a noise-limited environment and in an interference-limited environment. Several fast link adaptation methods are known for OFDM(A) systems—most of them are based on some calculation of a channel quality indicator (CQI). Fast and reliable link adaptation in an OFDM(A) systems depends on a measure of channel quality which remains accurate across a range of channel environments.